Combustion system and method of operation thereof

ABSTRACT

A combustion system using at least 90 wt % propylene glycol based liquid fuel includes a first fuel tank, a wick inserted in the first tank, a sensing unit configured to receive an activating signal and sense the liquid level of the propylene glycol based liquid fuel in the first fuel tank and send a fuel replenishment signal accordingly, a second fuel tank, a conduit system connected with the first and the second fuel tanks, and a drive unit connected with the conduit system and configured to receive the fuel replenishment signal so as to cause the propylene glycol based liquid fuel in the second fuel tank to replenish the first fuel tank through the conduit system as well as to cool the wick.

BACKGROUND OF THE INVENTION 1. Field of the invention

The present invention relates to a combustion system and method of operation thereof

2. Description of the Related Art

Current combustion systems, such as fireplaces, which can create warm and cozy atmosphere, mostly use an ethanol-based fuel, which is a To highly flammable liquid, which may lead to an explosion risk or burn injuries during the procedure of filling fuel. The risk is especially high especially after the fireplace is completely extinguished or cooled sufficiently. Further, when a fireplace accidentally falls, ethanol-based fuels can cause the fire to spread rapidly, Likewise, isopropanol, which is also frequently used as a fuel, suffers similar disadvantages as ethanol-based fuels.

It has now been found that the above problems can be overcome by using propylene glycol based fuels. Propylene glycol based fuels contain at least 60 wt % propylene glycol and have a flash point of at least higher than 50° C., which can even be as high as 104° C., depending on the compounding ratio. So propylene glycol based fuels are actually a non-inflammable flammable liquid fuel. “Non-inflammable” means that it won't catch fire when in contact with a flame (such as a match) at room temperature, and “flammable” means that it can burn under the right conditions. Further, burping propylene glycol based fuels will extinguish if poured onto a surface which is at a temperature the same as the ambient temperature, thereby preventing the fire from spreading.

Additionally, a wick is essential for supplying fuel to a flame and draws up the fuel by the capillary attraction. The wick may be made of, for example, glass fibers, ceramic fiber materials, silicate fiber materials or rock wool, or polymeric materials such as aramid fibers, cotton or porous materials such as pumice, or other wick materials known in the art. In contrast to wicks made of other materials, the metal wick does not produce carbonization and wear during combustion and so more suitable for burning propylene glycol based liquid fuels completely. However, metal wicks has a problem of getting overheated due to a good thermal conductivity of the metal, thereby affecting the flame size and transferring heat from the flame tip to the fuel.

Generally, when the flame is extinguished, the wick and the fuel are still hot, indicating that the fuel is evaporating to produce exhaust gas with toxic chemicals. While propylene glycol based fuel is a low smoke toxicity fuel, even the smallest amount of toxic chemicals can raise concerns regarding human health. Therefore, providing a combustion system that people can use without risk to their health and can be used in an environment with children and pregnant women is desirable.

The present invention is, therefore, intended to obviate or at least alleviate the problems encountered in the prior art.

SUMMARY OF THE INVENTION

According to the present invention, a combustion system using at least 90 wt % propylene glycol based liquid fuel includes a first fuel tank for containing the propylene glycol based liquid fuel, a wick for transmitting the propylene glycol based liquid fuel in the first tank, a sensing unit configured to receive an activating signal and sense the liquid level of the propylene glycol based liquid fuel in the first fuel tank and send a fuel replenishment signal accordingly, a second fuel tank for containing the propylene glycol based liquid fuel, a conduit system connecting the first fuel tank to the second fuel tank, and a drive unit connected with the conduit system and configured to receive the fuel replenishment signal so as to cause the propylene glycol based liquid fuel in the second fuel tank to replenish the first fuel tank through the conduit system as well as to cool the wick.

Further, a method of operating the combustion system includes preparing the combustion system; using the sensing unit to receive an activating signal and sense the liquid level of the propylene glycol based liquid fuel in the first fuel tank and send a fuel replenishment signal accordingly; and using the drive unit to receive the fuel replenishment signal so as to cause the propylene glycol based liquid fuel in the second fuel tank to replenish the first fuel tank through the conduit system, and to cause the propylene glycol based liquid fuel from the second fuel tank to cool the wick.

There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto.

In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

Further, the purpose of the abstract is to enable the public generally, and especially scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure. The abstract is neither intended to define the invention, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way,

Other objectives, advantages, and new features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanied drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a combustion system in accordance with the present invention.

FIG. 2 is a partial, cross-sectional view of the combustion system of FIG. 1 .

FIG. 3 is a flow chart illustrating the method of using the combustion system of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 and FIG. 2 are perspective and partial, cross-sectional views of a combustion system in accordance with the present invention respectively. The combustion system of the present invention uses at least 90 wt % propylene glycol based liquid fuel. The combustion system includes a first fuel tank 10, a second fuel tank 20, and a drive unit 40.

The first fuel tank 10 is for containing the propylene glycol based liquid fuel and includes a wick 11 inserted therein for transmitting the propylene glycol based liquid fuel in the first tank 10. Preferably, the wick 11 is made of non wool material. Preferably, the wick 11 is made of metal. Preferably, the wick 11 is made of carbon fiber. The first fuel tank 10 also includes a sensing unit 12 configured to receive an activating signal and sense the liquid level of the propylene glycol based liquid fuel in the first fuel tank 10 and send a fuel replenishment signal accordingly, i.e. when the liquid level is at a low predetermined level

The second fuel tank 20 is for containing the propylene glycol based liquid fuel. The second fuel tank 20 is connected to the first fuel tank 10 by a conduit system 30.

The drive unit 40 is connected with the conduit system 30 and configured to receive the fuel replenishment signal so as to cause the propylene glycol based liquid fuel in the second fuel tank 20 to replenish the first fuel tank 10 through the conduit system 30 as well as to cool the wick 11.

Before the wick 11 is lit, the sensing unit 12 can sense the liquid level of the propylene glycol based liquid fuel in the first fuel tank 10 in advance, and if the liquid level is low, it will send the fuel replenishment signal the driving unit 40. The signal causes the drive unit 40 to replenish the propylene glycol based liquid fuel in the second fuel tank 20 to flow into the first fuel tank 10 through the conduit system 30 until a high liquid level is achieved; on the contrary, a user can ignite the wick 11 if the liquid level is high. When the wick 11 is lit and starts to transmit the propylene glycol based liquid fuel in the first fuel tank 10 to a flame, once the sensing unit 12 senses that the propylene glycol based liquid fuel in the first fuel tank 10 is consumed to a low level, the fuel replenishing signal is sent to the drive unit 40, so that the drive unit 40 causes the propylene glycol based liquid fuel in the second fuel tank 20 to replenish the first fuel tank 10 through the conduit system 30, and the propylene glycol based liquid fuel from the second fuel tank 20 can not only supply fuel to and maintain the flame, but also cool the wick 11 heated by the flame so as to prevent the wick 11 from being overheated to affect the size and shape of the flame.

The above efficacy is based in particular on the high flash point characteristics of propylene glycol based fuels, utilizing the propylene glycol based liquid fuel from the second fuel tank 20 to cool the wick 11 that has been heated by the flame and stabilize the flame size and shape, generally Ethanol or isopropanol based fuels cannot be used in this way, because their flash point is extremely low, and they are ignited upon contact with the wick 11 heated by the flame, and cannot be used to cool the wick 11 at all.

In addition, the driving unit 40 is configured to receive a shutdown signal so as to pump the propylene glycol based liquid fuel in the first fuel tank 10 to the second fuel tank 20 by the conduit system 30. When the wick 11 is in the ignited state, once the driving unit 40 receives the shutdown signal, it starts to pump the propylene glycol based liquid fuel in the first fuel tank 10 to the second fuel tank 20 until the propylene glycol based liquid fuel is at a low level such that the wick 11 cannot generate a flame, or the propylene glycol based liquid fuel in the first fuel tank 10 is completely pumped to the second fuel tank 20 to extinguish the flame of the wick 11. Further, when the wick 11 is in the ignited state, it will conduct the heat of the flame to the propylene glycol based liquid fuel in the first fuel tank 10. Thus, when the propylene glycol based liquid fuel is pumped to the second fuel tank 20 the wick 11 is also cooled, thereby better cooling the environment temperature, This is the characteristic of the high flash point of propylene glycol based fuel, and the propylene glycol based liquid fuel in the first fuel tank 10 is cooled by the propylene glycol based liquid fuel from the second fuel tank 20.

Further, when the driving unit 40 receives the shutdown signal and pumps the level of the propylene glycol based liquid fuel in the first fuel tank 10 to a height that cannot be transmitted by the wick 11 to generate a flame, or after the propylene glycol based liquid fuel in the first fuel tank 10 is completely pumped to the second fuel tank 20 (sensed by the sensing unit 12), it continues operating fir a predetermined period of time so as to extract exhaust gas produced after the flame goes out through the conduit system 30.

In order to improve the cooling efficiency of the fuel, the volume of the first fuel tank 10 in this embodiment is smaller than the volume of the second fuel tank 20, and more preferably, the volume of the second fuel tank 20 is at least ten times larger than a volume of the first fuel tank 10.

Further, at least 90 wt % propylene glycol based liquid fuel used by the combustion system of the present invention can preferably contain 95 wt % propylene glycol.

Further, the conduit system 30 of the present invention can include a first conduit connecting the first fuel tank 10 to the drive unit 40 and a second conduit 32 connecting the second fuel tank 20 to the drive unit 40.

Further, the drive unit 40 includes a motor which is adapted to transmit the propylene glycol based liquid fuel in the second fuel tank 20 to the first fuel tank 10 through the conduit system 30, or to transmit the propylene glycol based liquid fuel in the first fuel tank 10 to the second fuel tank 20 through the conduit system 30.

FIG. 3 shows a method flowchart of operating the combustion system using at least 90 wt % propylene glycol based liquid fuel. The method includes preparing the combustion system, which has been described in detail above, and will not be repeated here for brevity; using the sensing unit 12 to receive an activating signal and sense the liquid level of the propylene glycol based liquid fuel in the first fuel tank 10 and send a fuel replenishment signal accordingly i.e. if the liquid level is not high enough for igniting the wick 11; using the drive unit 40 to receive the fuel replenishment signal so as to cause the propylene glycol based liquid fuel in the second fuel tank 20 to replenish the first fuel tank 10 through the conduit system 30, and to cause the propylene glycol based liquid fuel from the second fuel tank 20 to cool the wick 11, i.e. the propylene glycol based liquid fuel in the first fuel tank 10 reaches a height for igniting the wick 11 or maintaining the flame generated by the wick 11 in the ignited state, and it is worth noting that the wick 11 will heat up due to heat conduction in the ignited state, and the wick 11 can be cooled by supplementing the normal temperature propylene glycol-based liquid fuel from the second fuel tank 20 to achieve the cooling effect; and using the drive unit 40 to receive a shutdown signal and pump the propylene glycol based liquid fuel in the first fuel tank 10 to the second fuel tank 20 through the conduit system 30, and wherein the drive unit 40 continues operating for a predetermined period of time after receiving the shutdown signal and pumping the propylene glycol based liquid fuel in the first fuel tank 10 to the second fuel tank 20 so as to extract exhaust gas produced after the flame goes out.

The operating method of the combustion system further includes the steps that the driving unit 40 receives the shutdown signal, and accordingly, the propylene glycol based liquid fuel in the first fuel tank 10 is pumped to the second fuel tank 20 through the conduit system 30 until the propylene glycol based liquid fuel in the first fuel tank 10 is low and the wick 11 cannot generate a flame, or the propylene glycol based liquid fuel in the first fuel tank 10 is completely pumped to the second fuel tank 20, so that the flame of the wick 11 goes out.

After the driving unit 40 receives the shutdown signal and pumps the liquid level of the propylene glycol based liquid fuel in the first fuel tank 10 to a low level, or completely pumps the propylene glycol based liquid fuel in the first fuel tank 10 to the second fuel tank 20 (sensed by the sensing unit 12), it continues operating for a predetermined period of time to extract the exhaust gas generated by the extinguishment of the flame of the wick 11 through the conduit system 30.

The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention, 

What is claimed is:
 1. A combustion system using at least 90 wt % propylene glycol based liquid fuel, the combustion system comprising: a first fuel tank for containing the propylene glycol based liquid fuel, a wick for transmitting the propylene glycol based liquid fuel in the first tank, a sensing unit configured to receive an activating signal and sense the liquid level of the propylene glycol based liquid fuel in the first fuel tank and send a fuel replenishment signal accordingly a second fuel tank for containing the propylene glycol based liquid fuel, a conduit system connecting the first fuel tank to the second fuel tank, and a drive unit connected with the conduit system and configured to receive the fuel replenishment signal so as to cause the propylene glycol based liquid fuel iii the second fuel tank to replenish the first fuel tank through the conduit system as well as to cool the wick.
 2. The combustion system as claimed in claim 1, wherein the drive also configured to receive a shutdown signal so as to pump the propylene glycol based liquid fuel in the first fuel tank into the second fuel tank.
 3. The combustion system as claimed in claim 2, wherein the drive unit is configured to continue pumping the propylene glycol based liquid fuel in the first fuel tank into the second fuel tank for a predetermined time after receiving the shutdown signal.
 4. The combustion system of claim 1, wherein the volume of the first fuel tank is smaller than the volume of the second fuel tank.
 5. The combustion system as claimed in claim 4, wherein the volume of the second fuel tank is at least ten times larger than a volume of the first fuel tank,
 6. The combustion system as claimed in claim 1, wherein the propylene glycol based liquid fuel contains 95 wt % of propylene glycol.
 7. The combustion system as claimed in claim 1, wherein the conduit system includes a first conduit connecting the first fuel tank to the drive unit and a second conduit connecting the second fuel tank to the drive unit.
 8. The combustion system of claim 1, wherein the drive unit includes a motor.
 9. The combustion system as claimed in claim 1, wherein the wick is made of non wool material.
 10. The combustion system as claimed in claim 9, wherein the wick is made of metal.
 11. The combustion system as claimed in claim 9, wherein the wick is made of carbon fiber.
 12. A method of operating a combustion system using at least 90 wt % propylene glycol based liquid fuel, comprising: preparing a combustion system which includes: a first fuel tank for containing the propylene glycol based liquid fuel with a wick inserted therein for transmitting the propylene glycol based liquid fuel in the first fuel tank, and a sensing unit disposed therein; a second fuel tank for containing the propylene glycol based liquid fuel; a conduit system connecting the first fuel tank to the second fuel tank; and a drive unit connected with the conduit system using the sensing unit to receive an activating signal and sense the liquid level of the propylene glycol based liquid fuel in the first fuel tank and send a fuel replenishment signal accordingly; and using the drive unit to receive the fuel replenishment signal so as to cause the propylene glycol based liquid fuel in the second fuel tank to replenish the first fuel tank through the conduit system, and to cause the propylene glycol based liquid fuel from the second fuel tank to cool the wick.
 13. The method of operating the combustion system as claimed in claim 12 further comprising following steps: using the drive unit to receive a shutdown signal and pump the propylene glycol based liquid fuel in the first fuel tank to the second fuel tank through the conduit system, and wherein the drive unit continues operating for a predetermined period of time after receiving the shutdown signal and pumping the propylene glycol based liquid fuel in the first fuel tank to the second fuel tank so as to extract exhaust gas produced after the flame goes out,
 14. The combustion system as claimed in claim 9, wherein the wick is made of metal.
 15. The combustion system as claimed in claim 9, wherein the wick is made of carbon fiber. 